As a Mechanical Engineer, working in the machine-building industry, I got interested in the possibilities of IoT applications. So I started reading up on the subject of sensors, and data processing. I soon stumbled upon the Arduino environment. It's a relatively easy programming environment (C++) which can be used to program relatively cheap I/O boards of that same brand (or even cheaper Chinese clones thereof).
After some simpler projects with data collection from sensors, data manipulation, and outputting a response (like reading an RFID chip, checking against known chips, outputting an LED color dependent on the ID) I more or less accidentally found a website of a guy that had made a quadcopter flight controller out of an Arduino. Since I am interested in anything that flies, I sort of wanted to be able to do the same. But then again, I did not want to spend much money on a project with a high risk of failure, so I "chopped it up" in smaller pieces.
First of all, I would need a transmitter and a receiver, and let the receiver "talk" to the Arduino flightcontroller-to-be. The input of the Arduino would be a 4-channel PWM signal. That's a "Pulse Width Modulation" signal, which consists of one pulse per channel with a pulse length (width on a time plot) of 1000 micro seconds to 2000 micro seconds. The length corresponds to the stick position on the transmitter, so 1500 micro seconds is the middle position of the respective stick.
So I went online, and got me the cheapest transmitter / receiver combo I could find: an.FS-I6 transmitter, packaged with an FS-IA6 receiver
I'll spare you the programming details, but after connecting the receiver to the Arduino board, and connecting the Arduino board to an LCD screen, all powerder from a 9V battery, I could read the pulse lengths for each channel, an see that they exactly behaved like expected! 😃
So, now I was confident I would get it all to work. So I ordered a frame, and the power train, plus a brunch of small stuff to get me started (solder, shrink tube, that sort of things). I chose a beefy battery 5000 mAh, 30C 3S, to drive 4 2012 1000KV motors though 30 A ESCs, with 1045 props attached. As a frame, I chose a Q380.
It takes a while for those things to arrive from China, but the price difference is worth the wait, in my opinion. Plus, that would give me some time to complete the program with the most important bit of it all: the PID loop that calculates corrections to the motor control signals that are needed for stable flight. Once the parts were in, I started with laying them all out where I thought I would mount them. Always a good idea to do that before you cut any wires 😉
Then, after a bit of soldering, my first quadcopter was ready to spin up. This was the beginning of a new, addictive hobby... I felt that from the start!
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